A liquid crystal panel used in a liquid crystal display device, such as a liquid crystal television set, does not emit light by itself. Thus, such display device needs a backlight unit as a separate lighting unit. Such a backlight unit is installed on the rear side (opposite to the display surface) of the liquid crystal panel. The backlight unit is provided with: a chassis with an opening facing the liquid crystal panel; a light source housed in the chassis; optical members (such as a diffuser sheet) disposed in the opening of the chassis to face the light source and efficiently causing the light emitted by the light source to be output toward the liquid crystal panel; and a reflection sheet disposed in the chassis to face the optical member and reflecting the light toward the opening of the chassis.    Patent Document 1: Japanese Unexamined Patent Publication No. 2009-93156